• Allan Lipton, Laurie Goodman, Kim Leitzel, Jennifer Cook, Jeff Sperinde, Mojgan Haddad, Wolfgang J Köstler, Weidong Huang, Jodi M Weidler, Suhail Ali, Alicia Newton, Eva-Marie Fuchs, Agnes Paquet, Christian F Singer, Reinhard Horvat, Xueguang Jin, Joyee Banerjee, Ali Mukherjee, Yuping Tan, Yining Shi, Ahmed Chenna, Jeff Larson, Yolanda Lie, Thomas Sherwood, Christos J Petropoulos, Stephen Williams, John Winslow, Gordon Parry, and Michael Bates.
• Breast Oncology Research, Division of Hematology/Oncology, Department of Medicine, Penn State Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA. alipton@hmc.psu.edu
• Breast Cancer Res. Treat. 2013 Aug 1; 141 (1): 43-53.

AbstractTrastuzumab is effective in the treatment of HER2/neu over-expressing breast cancer, but not all patients benefit from it. In vitro data suggest a role for HER3 in the initiation of signaling activity involving the AKT–mTOR pathway leading to trastuzumab insensitivity. We sought to investigate the potential of HER3 alone and in the context of p95HER2 (p95), a trastuzumab resistance marker, as biomarkers of trastuzumab escape. Using the VeraTag® assay platform, we developed a dual antibody proximity-based assay for the precise quantitation of HER3 total protein (H3T) from formalin-fixed paraffin-embedded (FFPE) breast tumors. We then measured H3T in 89 patients with metastatic breast cancer treated with trastuzumab-based therapy, and correlated the results with progression-free survival and overall survival using Kaplan–Meier and decision tree analyses that also included HER2 total (H2T) and p95 expression levels. Within the sub-population of patients that over-expressed HER2, high levels of HER3 and/or p95 protein expression were significantly associated with poor clinical outcomes on trastuzumab-based therapy. Based on quantitative H3T, p95, and H2T measurements, multiple subtypes of HER2-positive breast cancer were identified that differ in their outcome following trastuzumab therapy. These data suggest that HER3 and p95 are informative biomarkers of clinical outcomes on trastuzumab therapy, and that multiple subtypes of HER2-positive breast cancer may be defined by quantitative measurements of H3T, p95, and H2T.

56 keywords...

hide…